What is the number if 5 is added to its twice the sum will be 25?
2 answers:
You might be interested in
Answer:
The 95% confidence interval for the difference between the proportion of all U.S. teens and adults who use social networking sites is (0.223, 0.297). This means that we are 95% sure that the true difference of the proportion is in this interval, between 0.223 and 0.297.
Step-by-step explanation:
Before building the confidence interval we need to understand the central limit theorem and the subtraction of normal variables.
Central Limit Theorem
The Central Limit Theorem estabilishes that, for a normally distributed random variable X, with mean and standard deviation
, the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean
and standard deviation
.
For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.
For a proportion p in a sample of size n, the sampling distribution of the sample proportion will be approximately normal with mean and standard deviation
Subtraction between normal variables:
When two normal variables are subtracted, the mean is the difference of the means, while the standard deviation is the square root of the sum of the variances.
Sample of 800 teens. 73% said that they use social networking sites.
This means that:
Sample of 2253 adults. 47% said that they use social networking sites.
This means that:
Distribution of the difference:
Confidence interval:
Is given by:
In which
z is the zscore that has a pvalue of .
95% confidence level
So , z is the value of Z that has a pvalue of
, so
.
Lower bound:
Upper bound:
The 95% confidence interval for the difference between the proportion of all U.S. teens and adults who use social networking sites is (0.223, 0.297). This means that we are 95% sure that the true difference of the proportion is in this interval, between 0.223 and 0.297.
Answer:
It is Milk
Step-by-step explanation:
The liquid in the bottle has mass given in grams and the mass of that substance is 117 grams.
The volume of the substance is 15 cubic centimeters.
Now, using the formula of density we can estimate which substance could it be.
, where 'd', is the density, 'm' is the mass, and 'v' is the volume of the substance.
Plugging the value of mass and volume we get:
So the density of the substance is 7.8 grams per cubic centimeter.
It cannot be water since the density of water is 1 grams per cubic centimeter.
It cannot be gasoline because its density is 0.77 grams per cubic centimeter.
It cannot be mercury because the density of mercury is 13.56 grams per cubic centimeter.
Since, the density in this case matches the density of thick milk and hence,therefore, the liquid in the bottle is milk.